2o (292 x 192 mm). General title, first state of the title with printer's woodcut device and without the text beginning "Accessit nunc...," 5 section titles, with the dedication to King James of England *2r-*4r (later suppressed by Kepler and absent from a few copies), errata leaf at end; 5 engraved plates, numerous woodcut diagrams and illustrations in text after W. Schickard, woodcut musical notation in Book III. (A1 with minor paper flaws, some light browning, tiny hole in O2 and O4.) Contemporary German vellum, spine with ink-lettered orange paper label.

FIRST EDITION OF KEPLER'S MAJOR COSMOLOGICAL TREATISE, an exposition of his theory of the harmony of the universe, and the work which describes the third law of planetary motion. Kepler had drafted a plan for the work already in 1599, but he was unable to return to it until 1616. The next two years saw the death of two of his children, and work on his Harmonices became a solace. All of his previous work and the insights into the working of the cosmos that he had gained in the intervening decades served as material for this, his life's work. "Certainly for Kepler this book was his mind's favorite child. Those were the thoughts to which he clung during the trials of his life and which brought light to the darkness that surrounded him... his Harmonices appears as a great cosmic vision, woven out of science, poetry, philosophy, theology, mysticism..." (Caspar, Kepler, 1959, p. 290, quoted in DSB). Kepler attempted to discern God's archetypal laws of the universe in four areas: geometry, music, astrology and astronomy. He conceived of a universal harmony as the embodiment of certain simple geometrical proportions relating these different aspects of the cosmos. In book I he studied the properties of polygons and polyhedrons, and introduced the great and small stellated dodecahedrons (rediscovered in 1810 by Louis Poinsot). In Book V, "on the harmony of celestial motion," Kepler refined the theory expounded in his Mysterium cosmographicum (1596), that the mean distances of the planets from the sun are in proportions related to spheres inscribing and circumscribing the five regular solids. "Now, imbued with a new respect for data, he could no longer dismiss [the earlier theory's] 5 percent error... In the astronomical book V... he came to grips with this central problem: By what secondary principles did God adjust the original archetypal model based on the regular solids?... In the course of this investigation, Kepler hit upon the relation now called his third or harmonic law" (DSB). In this he related the magnitude of the planetary orbits to their periods of revolution around the sun, and established that the square of a planet's periodic time is proportional to the cube of its mean distance from the sun.

A SUPERB ASSOCIATION COPY: MATTHIAS BERNEGGER, a native of Hallstatt in Upper Austria, was a History Professor, and a famed Strassburg humanist, when he meet Kepler on July 17, 1612. "Bernegger was the best and most faithful friend that Kepler ever found" (Caspar, p.226). Their scientific correspondence, lasting nearly two decades, Epistolae J. Keppleri & M. Berneggeri mutuae, was published in Strassburg by Josia Staedel in 1672. "In the domain of astronomy he had the credit of having translated Galileo's Italian Dialogue about the systems of the world into Latin, thereby assuring him of a wider circulation." (Caspar, p.226).